diff --git a/documents/by-course/math-8/course-notes/dvd.typ b/documents/by-course/math-8/course-notes/dvd.typ
index cb4d89b..1b6ae29 100644
--- a/documents/by-course/math-8/course-notes/dvd.typ
+++ b/documents/by-course/math-8/course-notes/dvd.typ
@@ -286,14 +286,23 @@
 #let example = example-style("item", "Example")
 
 #let proof(body, name: none) = {
-  thmtitle[Proof]
+  [_Proof_]
   if name != none {
     [ #thmname[#name]]
   }
-  thmtitle[.]
+  [.]
   body
   h(1fr)
-  $square$
+
+  // Add a word-joiner so that the proof square and the last word before the
+  // 1fr spacing are kept together.
+  sym.wj
+
+  // Add a non-breaking space to ensure a minimum amount of space between the
+  // text and the proof square.
+  sym.space.nobreak
+
+  $square.stroked$
 }
 
 #let fact = thmplain(
diff --git a/documents/by-course/pstat-120a/course-notes/dvd.typ b/documents/by-course/pstat-120a/course-notes/dvd.typ
index cb4d89b..1b6ae29 100644
--- a/documents/by-course/pstat-120a/course-notes/dvd.typ
+++ b/documents/by-course/pstat-120a/course-notes/dvd.typ
@@ -286,14 +286,23 @@
 #let example = example-style("item", "Example")
 
 #let proof(body, name: none) = {
-  thmtitle[Proof]
+  [_Proof_]
   if name != none {
     [ #thmname[#name]]
   }
-  thmtitle[.]
+  [.]
   body
   h(1fr)
-  $square$
+
+  // Add a word-joiner so that the proof square and the last word before the
+  // 1fr spacing are kept together.
+  sym.wj
+
+  // Add a non-breaking space to ensure a minimum amount of space between the
+  // text and the proof square.
+  sym.space.nobreak
+
+  $square.stroked$
 }
 
 #let fact = thmplain(